The figure is not drawn to scale. Three pentagons K, L and M are arranged as shown in the figure. The area of Pentagon K is
45 the area of Pentagon L. The area of Pentagon L is
25 the area of Pentagon M.
(a) Find the ratio of the area of Pentagon K to the area of Pentagon M.
(b)
34 of Pentagon K is shaded. What fraction of the whole figure is not shaded?
K |
L |
M |
4x2 |
5x2 |
|
|
2x5 |
5x5 |
8 u |
10 u |
25 u |
(a)
Area of Pentagon L is the repeated identity. Make the area of Pentagon L the same. LCM of 5 and 2 is 10.
Pentagon K : Pentagon M
8 : 25
(b)
Shaded part of Pentagon K
=
34 x 8 u
= 6 u
Unshaded part of Pentagon K
= 8 u - 6 u
= 2 u
Unshaded part of Pentagon M
= 25 u - 6 u
= 19 u
Total figure unshaded
= 19 u + 2 u
= 21 u
Total figure
= 25 u + 2 u
= 27 u
Fraction of the whole figure that is unshaded
=
2127=
79Answer(s): (a) 8 : 25; (b)
79